why when I rotate a point in a curve all the points is rotating?
When you are editing curves, selecting the point of the curve also selects the two control handles that define the curve going into and out of the control point. Rotating this selection moves all three and may not give the result you want.

Another property of the curves control point is Tilt, you can see this value under Transform in the properties sidebar N. When using a flat extrusion shape this can 'twist' the extrusion sideways without altering the curve shape.



You need to be cautious with it's use as a large tilt value compared to the next points can give a visible crease.